Ibuprofen may reduce the efficacy of furosemide and thiazide diuretics, due to prostaglandin synthesis inhibition at renal level. This feature must be considered in case of combined therapy.
Owing to a possible strengthening effect of oral anticoagulants, prothrombin time must be monitored during the 1st treatment week and a possible adjustment of the anticoagulant dose is to be scheduled in case of concomitant prolonged treatment.
A reduction of the hypotensive effect of β-blocking drugs, as well as a strengthening of the possible ulcerogenic effect after concomitant administration of corticosteroids can also be observed thus, requiring due caution in case of combined therapy. In some isolated cases, an increase in plasma levels of digoxin, phenytoin and lithium after concomitant administration of ibuprofen was reported.
Ibuprofen administration may occasionally increase methotrexate toxicity thus, requiring due caution in case of combined therapy. Ibuprofen must not be used in association with other NSAIDs eg, acetylsalicylic acid and paracetamol.
After concomitant administration of H2-antagonists, no significant effect on their plasma levels was observed.